Impact of oestradiol and progesterone on antioxidant activity in normal human breast epithelial cells in culture

Augmented oxidative stress in infertile women with persistent chlamydial infection

There is established association between oxidative stress, infections of genital tract and fertility. Genital tract infections may provoke increased production of free radicals and generate oxidative stress that can be involved in pathophysiology of a number of reproductive diseases and complications during pregnancy. The aim of this study was to determine connection between oxidative stress and infertility associated with persistent chlamydial infection. Serum samples of infertile women with tubal factor infertility (TFI), women with multiple spontaneous abortions (MSA) and fertile women was screened for C. trachomatis MOMP specific IgG and IgA antibodies and cHSP60 specific igG antibodies using ELISA. The levels of superoxide anion radical, nitric oxide and reduced glutathione were determined spectrophotometricaly. Serum levels of testosterone, luteinizing hormone and follicle stimulating hormone were determined by enzyme-linked fluorescent immunoassay method. Our results showed that persistent infection was more prevalent in TFI than in MSA group, whereas seropositivity was higher in MSA than in TFI group of patients. We also found that superoxide anion was significantly lower, while LH was markedly higher in TFI and MSA group of patients. However, when our results were analyzed according to the serological status of chlamydial infection, we found that parameters of oxidative stress, superoxide anion and index of oxidative stress, defined as relative ratio between superoxide anion and nitrites sum and glutathione ((O₂^-+NO₂^-)/GSH) were significantly elevated in infertile patients with persistent chlamydial infection compared to seropositive and seronegative patients. Our findings point to the possible impact of Chlamydia trachomatis infection on prooxidative-antioxidative balance that can influence fertility potential in women with persistent chlamydial infection.

Progesterone regulates the proliferation of breast cancer cells - in vitro evidence

Reports state that surgery performed at different phases of the menstrual cycle may significantly affect breast cancer treatment outcome. From previous studies, we identified differentially expressed genes in each menstrual cycle phase by microarray, then subjected them to functional in vitro analyses. Microarray studies disclosed genes that are upregulated in the luteal phase and follicular phase. TOB-1 is a tumor suppressor gene and was expressed exclusively in the luteal phase in our microarray study. Therefore, we further functionally characterized the protein product of TOB-1 in vitro. To our knowledge, no studies have yet been conducted on reactive oxygen species-regulated tumor suppressor interactions in accordance with the biphasic nature of progesterone. This work demonstrates that progesterone can produce reactive oxygen species in MCF-7 cells and that TOB-1 exerts a series of non-genomic interactions that regulate antiproliferative activity by modulating the antioxidant enzyme superoxide dismutase. Furthermore, this study implicates PTEN as an interacting partner for TOB-1, which may regulate the downstream expression of cell cycle control protein p27 via multiple downstream signaling pathways of progesterone through a progesterone receptor, purely in a time- and concentration-dependent manner. These results support the hypothesis that surgery conducted during the luteal phase of the menstrual cycle may facilitate improved patient survival.

Progesterone inhibits growth and induces apoptosis in cancer cells through modulation of reactive oxygen species

OBJECTIVE

Progesterone (P4) has been implicated as a protective factor for ovarian and endometrial cancers, yet little is known about its mechanism of action. We have shown apoptosis in ovarian and endometrial cancer cells with high doses of P4. Increased generation of reactive oxygen species (ROS) and an altered redox status have long been observed in cancer cells. The goal of this study was to assess the effect of P4 on cell growth, ROS generation, oxidative stress markers, and the expression of antioxidant proteins.

METHODS

All experiments were performed in vitro using cancer cell lines. Cell proliferation was determined using MTS proliferation assay. Production of ROS in cells was measured with the ROS indicator dye, aminophenyl fluorescein. Alterations in expression of antioxidant and apoptotic proteins were assessed by Western blotting.

RESULTS

The exposure of ovarian and endometrial cancer cell cultures to various doses of P4 caused a dose-dependent decrease in cell viability and the activation of caspase-3. Levels of ROS, markers of oxidative stress, and antioxidant proteins were elevated in cancer cells compared to normal cells and a marked decrease in their expression was seen following P4 treatment. In cancer cells, ROS was elevated while p-53 expression was low. P4 exposure of cells resulted in increased p-53 and BAX and decreased BCL-2 expression.

CONCLUSIONS

The data indicates that P4 has antioxidant effects. It alleviates ROS stress and causes apoptosis by upregulating proapoptotic (p-53 and BAX) and decreasing antiapoptotic (BCL-2) gene expression in cancer cells. These findings could have potential therapeutic implications.

Redox regulation in cancer: a double-edged sword with therapeutic potential

Oxidative stress, implicated in the etiology of cancer, results from an imbalance in the production of reactive oxygen species (ROS) and cell’s own antioxidant defenses. ROS deregulate the redox homeostasis and promote tumor formation by initiating an aberrant induction of signaling networks that cause tumorigenesis. Ultraviolet (UV) exposures, γ-radiation and other environmental carcinogens generate ROS in the cells, which can exert apoptosis in the tumors, thereby killing the malignant cells or induce the progression of the cancer growth by blocking cellular defense system. Cancer stem cells take the advantage of the aberrant redox system and spontaneously proliferate. Oxidative stress and gene-environment interactions play a significant role in the development of breast, prostate, pancreatic and colon cancer. Prolonged lifetime exposure to estrogen is associated with several kinds of DNA damage. Oxidative stress and estrogen receptor-associated proliferative changes are suggested to play important roles in estrogen-induced breast carcinogenesis. BRCA1, a tumor suppressor against hormone responsive cancers such as breast and prostate cancer, plays a significant role in inhibiting ROS and estrogen mediated DNA damage; thereby regulate the redox homeostasis of the cells. Several transcription factors and tumor suppressors are involved during stress response such as Nrf2, NFκB and BRCA1. A promising strategy for targeting redox status of the cells is to use readily available natural substances from vegetables, fruits, herbs and spices. Many of the phytochemicals have already been identified to have chemopreventive potential, capable of intervening in carcinogenesis.

Progestins induce catalase activities in breast cancer cells through PRB isoform: correlation with cell growth inhibition

Reactive oxygen species (ROS) have been suggested to participate in tumor emergence due to their mitogenic and apoptotic signaling, and as contributors to DNA structural damage. Here we report that progesterone and various synthetic steroids with progestin potencies (norethisterone acetate, MPA, and Tibolone) counteract cell growth induced by hydrogen peroxide (H(2)O(2)), through a potent induction of catalase activities, in breast cancer cells and normal human epithelial breast cells. At physiological concentrations, progesterone and the pure progestin, Org2058, displayed the most potent H(2)O(2) detoxification ability suggesting its effect was characteristic of its progestin potency. We also report on the enhancement of catalase activities by progesterone receptor isoform B (PRB), as determined from experiments using antiprogestins and MDA-MB-231, cells engineered for the selective expression of progesterone receptor isoform A or B. The potent action of progesterone on catalase activities indicates its contribution to a beneficial role in breast cell homeostasis.

Oxidative stress-related genotypes, fruit and vegetable consumption and breast cancer risk

Dietary antioxidants may interact with endogenous sources of pro- and antioxidants to impact breast cancer risk. A nested case-control study of postmenopausal women (505 cases and 502 controls) from the Cancer Prevention Study-II Nutrition Cohort was conducted to examine the interaction between oxidative stress-related genes and level of vegetable and fruit intake on breast cancer risk. Genetic variations in catalase (CAT) (C-262T), myeloperoxidase (MPO) (G-463A), endothelial nitric oxide synthase (NOS3) (G894T) and heme oxygenase-1 (HO-1) [(GT)(n) dinucleotide length polymorphism] were not associated with breast cancer risk. Women carrying the low-risk CAT CC [odds ratio (OR) = 0.75, 95% confidence interval (CI) 0.50-1.11], NOS3 TT (OR = 0.54, 95% CI = 0.26-1.12, P-trend = 0.10) or HO-1 S allele and MM genotype (OR = 0.56, 95% CI = 0.37-0.55), however, were found to be at non-significantly reduced breast cancer risk among those with high vegetable and fruit intake (> or = median; P-interactions = 0.04 for CAT, P = 0.005 for NOS3 and P = 0.07 for HO-1). Furthermore, those with > or = 4 putative low-risk alleles in total had significantly reduced risk (OR = 0.53, 95% CI = 0.32-0.88, P-interaction = 0.006) compared with those with < or = 2 low-risk alleles. In contrast, among women with low vegetable and fruit intake (< median), the low-risk CAT CC (OR = 1.33, 95% CI = 0.89-1.99), NOS3 TT (OR = 2.93, 95% CI = 1.38-6.22) and MPO AA (OR = 2.09, 95% CI = 0.73-5.95) genotypes appeared to be associated with raised breast cancer risk, with significantly increased risks observed in those with > or = 4 low-risk alleles compared with participants with < or = 2 low-risk alleles (OR = 1.77, 95% CI = 1.05-2.99, P-interaction = 0.006). Our results support the hypothesis that there are joint effects of endogenous and exogenous antioxidants.

Effect modification by catalase genotype suggests a role for oxidative stress in the association of hormone replacement therapy with postmenopausal breast cancer risk

Catalase, a ubiquitous heme enzyme, catalyzes conversion of hydrogen peroxide to water and molecular oxygen, protecting cells from oxidative stress. A C/T polymorphism in the promoter region of the CAT gene (rs1001179) affects transcriptional activity and RBC catalase levels. Oxidative stress may explain the observed increased postmenopausal breast cancer risk associated with hormone replacement therapy (HRT). We examined CAT genotype, HRT, and postmenopausal breast cancer risk in the Western New York Exposures and Breast Cancer case-control study. Cases (n = 616) were women with primary, incident, pathologically confirmed breast cancer. Randomly selected controls (n = 1,082) were frequency matched to cases on age and race. Genotype was assayed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) adjusted for potential confounders. CAT genotype alone was not associated with breast cancer risk. Ever use of HRT was associated with increased risk (OR, 1.39; 95% CI, 1.11-1.75). The increase with ever use was more pronounced among those with variant CT or TT CAT genotype (OR, 1.88; 95% CI, 1.29-2.75) than among those with CC (OR, 1.15; 95% CI, 0.86-1.54). Similarly, risk associated with >or=5 years of HRT use was greater among those with at least one variant T allele (OR, 2.32; 95% CI, 1.50-3.59). Increased risk was limited to estrogen receptor-positive tumors. Our findings suggest that CAT genotype modifies the effect of HRT use on breast cancer risk and that HRT may affect risk by affecting oxidative stress.

Redox features of the cell: a gender perspective

Reactive oxygen and nitrogen species have been implicated in diverse subcellular activities, including cell proliferation,differentiation and, in some instances, cell injury and death. The implications of reactive species inhuman pathology have also been studied in detail. However, although the role of free radicals in the pathogenesis of human diseases has been extensively analyzed in different systems (i.e., in vitro, ex vivo, and in vivo),it is still far from elucidated. In particular, the possible role of gender 4 differences in human pathophysiology associated with reactive species is a promising new field of investigation. Although the complex scenario this presents is still incomplete, important gender-associated "redox features" of cells have already been described in the literature. Here we summarize the different aspects of redox-associated molecules and enzymes in regard to gender differences in terms of the intracellular production and biochemical activity of reactive species. These are often associated with the pathogenetic mechanisms underlying several human morbidities(e.g., degenerative diseases) and can represent a specific target for new pharmacologic strategies. Gender differences may thus pose an important challenge for future studies aimed at the clinical management of diseases characterized by a redox imbalance.

beta-Sitosterol modulates antioxidant enzyme response in RAW 264.7 macrophages

Uncontrolled production of reactive oxygen species contributes to the pathogenesis of diseases such as cancer and cardiovascular disorders. Olive oil exerts remarkable preventive effects on the development of these diseases, which may be due to the action of various components of the olive oil. In fact, several findings suggest that minor components, like phytosterols such as beta-sitosterol, are responsible, at least in part, for these beneficial effects. Our results show that beta-sitosterol reverts the impairment of the glutathione/oxidized glutathione ratio induced by phorbol esters in RAW 264.7 macrophage cultures. These data can be correlated with the increase in manganese superoxide dismutase and glutathione peroxidase activities and the decrease in catalase activity. We also demonstrate that the effects of beta-sitosterol on antioxidant enzymes depend on the estrogen/phosphatidylinositol 3-kinase pathway.

Effects of steroid hormones on catalase activity in neuronal and glial cell systems

The aim of the present study was to determine short- (1 and 3 h) and long-term (24 h) effects of glucocorticoids [GCs; corticosterone (CORT), dexamethasone (DEX) and 6-methylprednisolone (6-MP)] and gonadal steroids [GSs; 17beta-estradiol (E2), progesterone (PROG) and testosterone (TEST)] on the activity of the hydrogen-peroxide-detoxifying enzyme catalase (CAT) in neural hippocampal HT22 cells and glial C6 cells because such effects have been described in peripheral organ systems. In HT22 cells, only long-term treatment with glucocorticoids (10(-5) M) induced effects on catalase activity, whereas gonadal steroids (10(-5) M) affected catalase activity after both short- and long-term incubations. At a lower concentration of 10(-7) M, glucocorticoids exerted only short-term treatment effects on catalase activity, while gonadal steroids (10(-7) M) affected the enzyme activity after short- and long-term treatments. In C6 glial cells, both glucocorticoids (10(-7) M) and gonadal steroids (10(-7) M) induced short- and long-term treatment effects. Thereby, our data show that steroid hormones differentially regulate catalase activity in models of the central nervous system (CNS) in a time- and steroid-dependent manner.

Sex hormone-induced alterations in the activities of antioxidant enzymes and lipid peroxidation status in the prostate of Noble rats

BACKGROUND

Oxidative stress has been implicated in prostate carcinogenesis. In the Noble rat model, treatment of rats with testosterone (T) plus 17beta-estradiol (E(2)) induced dysplasia and adenocarcinoma. Previous reports from us and other have indicated a linkage between steroid hormones and oxidative status in prostate cells in vivo and in vitro. Here, we provide further evidence that androgens and estrogens could induce a lobe-specific shift of prooxidant-antioxidant balance and alterations in antioxidant enzyme activities, leading to oxidative stress in the rat prostate gland in vivo.

METHODS

Male Noble rats were subjected to single (T, E(2), or diethylstilbestrol [DES] alone) or combined (T + E(2) or T + DES) hormone treatments. Lipid peroxidation status and antioxidant enzyme activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD) were assayed spectrophotometrically.

RESULTS

Treatment of rats with T did not alter lipid peroxidation in either the ventral prostate (VP) or the dorsolateral prostate (DLP). In contrast, exposure of rats to DES or E(2) modestly elevated lipid peroxidation in rat VP or DLP, respectively. Of importance, T + DES and T + E(2) treatments of rats induced marked increases in lipid peroxidation in the VP and the DLP, respectively. Antioxidant enzyme activities in the VP and DLP exhibited differential responses to sex hormone challenges. The activities of catalase, GPx, GR, and G6PD were mostly suppressed in either single or dual hormone-treated DLP, whereas there is a general increase of GR and G6PD activities in the VP after hormonal exposures. The changes in T + DES-treated VP were most dramatic with a marked activation of GPx (by one-fold), GR (by one-fold), and G6PD (by five-fold).

CONCLUSION

The lobe-specific differential responses of hormone-induced oxidative stress and modulations of antioxidant enzymatic defenses in the rat prostate suggest that reactive oxygen species may play a role in hormone-induced prostate carcinogenesis.

Influence of estradiol and gestagens on oxidative stress in the rat uterus

OBJECTIVE

We studied the effect of ovariectomy, estradiol (E2), and E2 + medroxyprogesterone (MPA) on the Wistar rat uterus.

METHODS

We used 15 adult female rats. The study was divided into the following four stages: (a) extirpation of the upper half of the left hemi-uterus (basal state) and ovariectomy; (b) animals were maintained for 15 days without treatment, performance of a new laparotomy, and extirpation of the remaining left hemi-uterus (OVX state); (c) beginning of E2 replacement therapy (ERT) (8 microg/day) for 15 days, followed by extirpation of the upper half of the right hemi-uterus (ERT state); and (d) the administration of E2 was continued, and oral treatment with MPA was begun (20 microg/day) to last for a further 15 days. At the end of the combined hormone replacement therapy (HRT) the remaining right hemi-uterus was extirpated (HRT state). At the end of each intervention, the plasma concentrations of E2 and PRG were measured.

RESULTS AND DISCUSSION

The ovariectomy significantly reduced the malonaldehyde (MDA) levels (P < 0.0008) and catalase activity (P < 0.0006). The ERT very significantly (P < 0.0033) raised the catalase and MDA levels; these significance levels were maintained after the Bonferroni method was applied (overall error 5%). The HRT reduced the levels of MDA and catalase, but not significantly after the Bonferroni test was applied.Conclusions. Uterine oxidative stress is increased by E2, resulting in a significant increase in MDA. This may be modulated in part by the catalase activity. Although it cannot be confirmed categorically, MPA seems to intervene by decreasing the said oxidative stress.

Influence of estrogen replacement therapy on plasma lipid peroxidation

OBJECTIVE

To observe whether any relationship exists between the concentration of plasma estradiol (E2) and the plasma concentrations of malondialdehyde (MDA) or whether a relationship exists between the concentration of plasma E2 and the activity of the erythrocyte enzymes, superoxide dismutase (SOD) and catalase, in ovariectomized female Wistar rats (treated and untreated with E2).

DESIGN

We used 40 ovariectomized Wistar rats randomly assigned to four groups. The first group was allowed to evolve freely with no treatment. A gel containing 17beta-estradiol was administered transdermally to the other three groups at doses of 4, 8, and 16 microg/day, respectively. After 15 days of treatment, blood samples were obtained from the four groups. The concentrations of plasma MDA and E2 and the activities of erythrocyte catalase and SOD were determined.

RESULTS

There were significant correlations between the MDA levels and the logarithm (base 10) of the plasma E2 concentrations in both linear (p = 0.00093) and quadratic (p = 0.000001) regression analyses. No relationship was found between the E2 concentrations and the catalase and SOD activities.

CONCLUSIONS

There was a clear relationship between the plasma levels of MDA and the logarithm of the plasma E2 concentrations, which was best demonstrated with a quadratic regression. This model may explain the contradictory findings presented by estrogens with respect to their pro-or antioxidant action.

Influence of estradiol on oxidative stress in the castrated rat uterus

OBJECTIVE

We set out to study how the concentration of estradiol influences oxidative stress (malondialdehyde) and the superoxide dismutase and catalase antioxidant systems in the castrated female Wistar rat uterus.

METHODS

We used 28 castrated female Wistar rats: 7 were left to evolve freely and the rest were divided into three groups of 7 animals receiving respective doses of 4, 8, and 16 microg/day of estradiol (E2) for 15 days. At the end of the study period, we determined the plasma concentrations of E2 and the concentrations of malondialdehyde (MDA) and superoxide dismutase and catalase activities in the uterus.

RESULTS

There was a significant correlation (P < 0.000028) between the uterine malondialdehyde levels and the logarithm (base 10) of the plasma E2 concentrations and also between malondialdehyde and the uterine catalase activity (P < 0.002). The regression plane that best fitted the correlation among the three variables was MDA = 10.21 + 12.88 x Log [E2] - 0.49 x catalase activity. We found no significant relationships with the superoxide dismutase activity.

CONCLUSIONS

There was a linear correlation between the base-10 logarithm of the estradiol plasma concentration and the phenomenon of uterine lipid peroxidation as measured by the MDA concentration in the uterus. This phenomenon was in part modulated by the inverse linear relationship between the antioxidant activity of the uterine catalase and the concentration of uterine MDA.

Increased formation of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine, in human breast cancer tissue and its relationship to GSTP1 and COMT genotypes

Reactive oxygen species (ROS) induced damage to DNA plays a major role in carcinogenesis. In order to estimate the level of oxidative damage and its role in breast cancer, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was determined in DNA isolated from human breast tissue. Furthermore, we investigated whether polymorphisms in genes for enzymes involved in generation and elimination of ROS had any association with the level of 8-OHdG in breast tissue. In this study, the level of 8-OHdG in DNA was measured by the high performance liquid chromatography-electrochemical detector (HPLC-ECD) method. Genotypes of cytochrome P450 (CYP)1A1, glutathione S-transferase (GST)M 1, GSTP1 and catechol O-methyltransferase (COMT) were determined by PCR-based restriction fragment length polymorphism analysis. A total of 61 Japanese patients were included in the study. The mean level of 8-OHdG in DNA of breast cancer tissues was 2.07 +/- 0.95 per 10(5) dG residues, while the mean level of 8-OHdG in DNA of non-cancerous breast tissues was 1.34 +/- 0.46 per 10(5) dG residues. The 8-OHdG levels in DNA of breast cancer tissues were significantly higher than those of their corresponding non-cancerous breast tissues (P < 0.0001). There was negative correlation between the clinical stage and the mean level of 8-OHdG in DNA of breast cancer tissues. Furthermore, patients with genotype of high GSTP1 activity had lower level of 8-OHdG in DNA of breast cancer tissues than others. On the contrary, the mean level of 8-OHdG in DNA of breast cancer tissues was higher among patients with genotype of high COMT activity. Our findings support the assumption that cancer cells are more exposed to oxidative stress than adjacent non-cancerous tissue. Genetic polymorphisms in enzymes involved in ROS metabolism may have a role in individual susceptibility to oxidant-related breast disease. At the same time, reduction of oxidative stress is thought to be a very important measure for primary prevention of breast cancer.

Uterine glutathione reductase activity: modulation by estrogens and progesterone

The aim of this study was to determine whether glutathione reductase activity in uterine tissue is regulated by sex hormones. In spayed rats uterine glutathione reductase was significantly increased by exogenous estrogen (P< 0.01), progesterone (P< 0.01) or estrogen plus progesterone (P<0.01). When enzyme activity is expressed per mg protein, daily administration of estrogen or progesterone induces a progressive increase of this enzyme between 24 to 48 h or 24 to 72 h of treatment, respectively. Whereas the combination of both steroids causes an earlier and higher increase in glutathione reductase activity at 24 h of treatment. Estradiol singly or in combination with progesterone induced the highest protein concentration in the uterus. Whereas uterine DNA concentration is only significantly affected by estradiol. Our results suggest that uterine glutathione reductase is regulated by estradiol and progesterone and may be involved in maintaining levels of reduced glutathione in the uterus. This compound may be required for control of the redox state of thiol groups and in detoxification reactions involving H2O2 and electrophylic substances. The antioxidant action of estrogens is partially due to the stimulation of glutathione reductase.

Protection by alpha-tocopherol but not ascorbic acid from hydrogen peroxide induced cell death in normal human breast epithelial cells in culture

Alpha-tocopherol and ascorbic acid have been suggested to play a role in breast cancer prevention due to their antioxidative capacity. Increased exposure to endogenous and exogenous sex steroids is a known risk factor for breast cancer. We have studied the effects of alpha-tocopherol and ascorbic acid on hydrogen peroxide induced cell death in sex hormone treated normal breast epithelial cells in culture. We found that alpha-tocopherol but not ascorbic acid alone protected the cells. The effect of alpha-tocopherol increased when ascorbic acid was added to the cultures. The hydrogen peroxide degradation rate decreased in cultures treated with alpha-tocopherol alone and in combination with ascorbic acid compared to cells grown in medium or with ascorbic acid only. Oestradiol and progesterone treatment did not influence the results. Possible beneficial effects of combining various antioxidants, endogenous as well as exogenous, on human breast tissue need to be investigated further both in vivo and in vitro.